Stator with a contact apparatus

ABSTRACT

A stator of an electric motor includes a stator main body which supports coils each having two coil ends of a multiphase stator winding. A contact apparatus is disposed on the end face of the stator main body and has an interconnection housing that receives a number of busbars for interconnecting the coils and a number of phase connections. Each phase of the stator winding is formed by at least one of the coils and at least one of the busbars as well as one of the phase connections. The dimensions of the busbars are set in such a way that the electrical resistance of all of the phases of the stator winding is the same. An electric motor having the stator is also provided.

The invention relates to a stator having a contact apparatus for contacting coils of a stator winding. The invention further relates to an electric motor, in particular an electronically commutated steering motor of a motor vehicle, having such a stator.

Motor vehicles nowadays usually have a number of adjusting parts, for example a steering system, a seat adjustment system, an actuatable lock, window lifter, an adjustable sunroof, which are adjustable or movable between different setting positions by means of an associated electromotive drive.

An electric motor, in particular brushless electric motor, as electric three-phase machine generally has a stator with a number of stator teeth, which are arranged for example in a star shape and support an electric rotary-field or stator winding in the form of individual coils, which are wound from an insulating wire. The coils are associated with their coil ends (winding wire ends) to individual strands or phases and are connected to one another in a predetermined way and are guided to phase connections to energize the rotary-field winding.

In the case of a brushless electric motor as a three-phase, electronically commutated three-phase machine, the stator has three phases and thus at least three phase conductors or phase windings, which are each suppled with electric current shifted in phase in order to generate a magnetic rotary field, in which a rotor that is usually provided with permanent magnets rotates. The phase ends of the phase windings are guided to a motor electronics unit for to control the electric motor. The coils of the rotary-field winding are connected here in a start circuit or in a delta circuit and electrically contacted with the three phase connections.

To guide and connect the coil ends, contact apparatuses in the form of interconnection systems or switch units are usual, which are fitted on an end face of the stator or of a stator assembly. Contact apparatuses of this kind are used in particular to electrically conductively connect the coil ends of the winding wire portions forming the coil windings, so that individual coil ends are electrically connected to one another (short-circuited) and therefore the coil or phase windings can be energized in series.

Contact apparatuses of this kind often have a number of integrated or overmolded conductor tracks or busbars as connection conductors for connection or contacting of the coil ends. When assembling the electric motor or busbars, the coil ends are contacted with the busbars so that coils associated with a common phase are connected to one another via the contacting apparatus. The coil ends are contacted with the busbars generally by means of an integrally bonded connection, for example by means of soldering or welding, in particular by means of laser welding.

Document DE 10 2010 039 335 A1 discloses a contact device of a stator of an electric motor, by means of which a number of coils arranged circumferentially of the stator are electrically contacted. The contact device has an annular contact support made of an electrically insulating material and also, for contacting the coils, electrically conductive conductor tracks, which are energized via axially protruding phase connections and are received in various planes lying parallel to the contact support plane.

It is conceivable that, by means of such a contact device (switch unit), which is arranged at an end face of a stator assembly with a stator main body supporting coils, not all coils are connected to one another. Due to the connection of the coils or their coil ends to the contact device, an at least two-phase (2-phase), preferably a three-phase (3-phase) electric motor is created. The contact device, which forms the interface between the stator and a motor electronics unit, has a number of connection elements (connection terminals) which generally corresponds to the number of phases.

A typical characteristic of the conductor tracks of the contact device, which is generally made of a material that is a good electrical conductor, preferably of copper or a copper alloy or of aluminum or an aluminum alloy, can be seen in the fact that they are laid over the shortest, often most intuitive path. Here, a predefined minimum distance between adjacent conductor tracks must not be undershot, whereby the electrical (ohmic) resistance is kept small (slight, low). The conductor track cross section in this case is usually constant within a conductor track or between the conductor tracks.

A disadvantage of this method of laying of the conductor tracks is that the symmetry of the (electrical) resistances measurable from the outside, in particular in the case of small coil resistances, may vary greatly, even if the coil resistances themselves are identical. This asymmetry may have a disadvantageous effect on the closed-loop and/or on the open-loop control of the electric motor by the electronics unit (motor electronics unit) and may generate an increased torque ripple and/or a high noise level.

The object of the invention is to describe a stator having a particularly suitable contact apparatus. In particular a torque ripple and/or a noise level is to be kept to a minimum by means of the contact apparatus. For this purpose, the greatest possible resistance symmetry of the phases is preferably to be produced. Furthermore, a particularly suitable electric motor having a stator of this kind is to be described.

The object is achieved in accordance with the invention by the features of claim 1 with regard to the stator and by the features of claim 10 in respect of the electric motor. Advantageous embodiments and developments are the subject matter of the dependent claims. The advantages and embodiments described in view of the stator are transferrable correspondingly also to the electric motor, and vice versa.

The stator has a stator main body, which extends along a stator axis and which supports a number of coils of a multi-phase winding, wherein each coil has two, in particular axially oriented, coil ends. The stator furthermore has a contact apparatus, which is arranged on an end face of the stator main body and which has a preferably annular interconnection housing that receives a number of busbars for interconnecting the coils and a number of phase connections, each of which is connected to one of the busbars. The stator winding is embodied in a suitably redundant manner, in particular with two lots of three phases.

Each phase of the stator winding is formed by at least one of the coils and at least one of the busbars as well as one of the phase connections, wherein the dimensions of the busbars are set in such a way that the electrical resistance of all of the phases of the stator winding is the same. The dimensions of the busbars are suitably set in such a way that the electrical resistance of the busbars is the same. For this purpose, the bar length and/or the bar cross section of the busbars is (are) advantageously set in such a way that the electrical resistances of the phases of the stator winding are the same. Each busbar expediently has at least one connection contact for contacting one of the coil ends.

With a suitable shape (geometry) of the busbar with a conductor track length or busbar length specified in respect of the particular resistance, it is also possible to bridge a distance, which by comparison with this length is small, between the contact points to be connected to this busbar, for example between the coil ends to be connected or those with a phase connection, by forming the corresponding busbar in an undulating, meandering or loop-like manner, for example. In other words, the corresponding busbar can be — even significantly — longer than the smallest distance between the contact points to be connected of the corresponding coils and/or the particular phase connection.

In an advantageous embodiment, the coils and their coil ends are arranged on the stator main body in such a way that a coil end of each of the coils is arranged on a radially inner circumference of the stator. In particular, with an arrangement of this kind of these coil ends, it is advantageously made possible that those busbars connecting the coils of a particular phase are the same for each of the phases.

In an advantageous embodiment, the coils are interconnected in a star circuit. To produce the star point of the star circuit, merely one individual busbar is used, which has three connection contacts and two busbar rail portions extending therebetween, which preferably have different portion lengths. The setting of the desired resistance symmetry can thus be simplified advantageously.

The invention is based on the consideration that an increased torque ripple and/or an increased noise level can be avoided if the electrical resistance of all phases of the stator winding or motor winding is the same. Since the electrical resistances of the coils involved in the stator winding are typically the same or identical, it has been found that the resistance symmetry can be optimized by adapting the resistances of the conductor tracks or busbars.

The resistances are generated here either by a change in cross section or by a change in length of all or certain busbars (conductor tracks). In this case, the busbars can have different cross sections from one another. The cross section can also vary along an individual busbar. Due to the change in length, for example due to an additional loop or a wave shape, the busbars (conductor tracks) are no longer necessarily laid over the shortest or most intuitive path. The cross sections can also vary here within an individual busbar.

A resistance symmetry of this kind can be produced in the case of electric motors having coils interconnected in a star circuit and in a delta circuit as well as in the case of electric motors having redundant windings, for example two three-phase stator windings (2 x 3 phases). Due to the very good resistance symmetry, electric motors of this kind can be controlled in a particularly exact manner and at the same time generate no or only minor torque ripples or noise.

In a further advantageous embodiment, the busbar to be connected to the phase connection has a joining end, which reaches through a corresponding, preferably rectangular recess of a connection portion of the phase connection. The busbar to be connected to the phase connection expediently has a joining end (fixing end), which reaches through the corresponding recess of the connection portion of the phase connection. The joining end of the busbar is suitably deformed or re-shaped in the connection (joint) to the phase connection, thus forming a, for example mushroom-head-shaped, fixing head overlapping the recess at least in some regions. This connection is particularly preferably produced as a welded connection, expediently by means of laser welding. The phase connections are suitably formed as insulation displacement contacts.

In the case of electric motors with redundant stator winding, i.e. in the case of redundant motors with a plurality of sub-systems accordingly, in which only one sub-system is controlled, the deviation of the current from the other sub-system in motor operation is low, which in turn improves the controllability. In addition, the (direct) current of the energized stator winding or the phases can be estimated more precisely.

In a preferred application, the above-described stator is part of an electric motor of a motor vehicle. The electric motor according to the invention is preferably a steering motor here, for example inclusive of a gearing, for the steering of the motor vehicle.

Exemplary embodiments of the invention will be explained in further detail hereinafter with reference to a drawing, in which:

FIG. 1 shows a schematic and simplified illustration of an electric motor of a motor vehicle;

FIG. 2 shows a perspective view of a stator and a contact apparatus, which is fitted or can be fitted on an end face of the stator and has an interconnection housing and phase connections (phase contacts) protruding therefrom and contact lugs of busbars for the interconnection of coils of a redundant stator winding;

FIG. 3 shows a perspective illustration of the contact apparatus without interconnection housing and with joints between joining ends of individual busbars and connection portions of the phase connections;

FIG. 4 shows a plan view of the contact apparatus without interconnection housing with a view of the coils, interconnected by the busbars of different bar length, bar cross-sections and bar shape, and their coil ends of a first and second sub-system of the redundant stator winding; and

FIGS. 5 a and 5 b schematically show the coils and their interconnection to the (redundant) phases of the first or second sub-system in a star circuit.

FIG. 1 shows a schematic and simplified illustration of an electric motor 1 for use in a motor vehicle. The electric motor 1 has a stator 2 with a multi-phase rotary-field or stator winding 3, which, for energization, is connected to a motor electronics unit 6 by means of phase connections 4 of a contact apparatus 5 (FIGS. 2 to 4 ) also referred to hereinafter as phase contacts. In the energized state the stator winding 3 generates a magnetic rotary field, which drives a rotor (not shown in greater detail) of the electric motor 1. The electric motor 1 is in particular an electronically commutated steering motor of a motor vehicle.

In the schematic illustration, the stator winding 3 is of three-phase configuration with three (motor) phases U, V, W. Each phase U, V, W is formed from a phase winding, which in the exemplary embodiment is formed by an interconnection of two coils (coil winding) 7 of the stator winding 3. The phases U, V, W are interconnected in this exemplary embodiment in a star circuit with a star point B.

FIG. 2 shows a perspective view of the contact apparatus or switch unit 5 for the stator 2. In this exemplary embodiment the stator winding 3 is formed redundantly with two lots of three phases U, V, W. In the assembled state, the contact apparatus 5 is fitted on an end face of the stator 2 or on the stator main body 8 thereof, embodied as a stator assembly and extending along the stator axis A and thus in the axial direction (axially). This or the stator assembly of the stator 2 for example comprises twelve inwardly directed stator teeth, to which the stator winding or rotary-field winding 3 of the electric motor 1 is applied in two sub-systems each having three phases U, V, W.

The coils 7 are wound in the exemplary embodiment on insulating winding supports or coil supports 9 and are fitted with the latter onto the stator teeth of the stator main body 8. Each of the frame-like winding supports 9 in this case supports a coil 7 as part of the stator winding 3. The coils 7 each have two axially directed coil ends 10. The coils and their coil ends are provided in FIG. 2 merely by way of example with the reference signs 7 and 10.

The coil ends 10 of the coils 7 are interconnected by means of the contact apparatus 5 fitted on an end face of the stator 2 to form the three-phase (3-phase) stator winding or rotary-field winding 3, which is redundant in this exemplary embodiment. In electromotive operation, the energized windings of the stator winding 3 each generate a stator-side magnetic field, which interacts with permanent magnets of a rotor of the brushless electric motor 1 rotating about the central stator or motor axis A. By means of the motor electronics unit 6, it is possible to switch to other phases U, V, W for energization of the latter, for example if individual phases U, V, W drop out as the result of a defect.

The contact apparatus 5 has a circular ring-shaped interconnection housing 11 made of electrically insulating material. The coil ends 10 of the coils 7 are guided through radially inwardly arranged, axial through-openings 12 of the interconnection housing 11 and are contacted on the upper side of the interconnection housing 1 to contact lugs 13 for interconnection. The through-openings 12 and contact lugs 13 are provided in the figures with reference signs merely by way of example.

The contact apparatus 5 is fastened or fastenable to the stator main body 8 in a form-locking and/or force-locking engaged manner by means of axial detent tongues 14 of the interconnection housing 11. The detent tongues 14 are distributed here on the outer circumference and are arranged on the (lower) side of the interconnection housing 11 facing the stator main body 8. The stator main body 8 in this case has, on its outer circumference, axially running grooves 15 in which the detent tongues 14 engage in a clamped manner for fastening. The contact apparatus 5 arranged on the corresponding end face of the stator 2 is releasably latched or fastened in a clamped manner to the stator main body 8.

As can be seen in conjunction with FIG. 3 , the contact apparatus 5 has a number of busbars 16 as connection conductors for interconnection of the coil ends 10 or contact lugs 13 thereof to the phase connections 4. The interconnection housing 11, in which the busbars 16 are received in a manner running concentrically with one another at least in some portions, is embodied as a plastics overmolding of the busbars 16. Here, the end-face contact lugs 13 of the busbars 16 and joining ends 17 of some of the busbars 16 provided normally for connection to the phase connections 4 are accessible, that is to say are not enclosed by the interconnection housing 11, at least in some portions.

The six phase connections 4 in the exemplary embodiment provide three connection pairs for the phases U, V, W of the three-phase stator winding or rotary-field winding 3 formed by the coils 7 and interconnection thereof. Each of the connection pairs with the three phases U, V, W and the associated busbars 16 forms one of two redundant sub-systems of the stator winding 3.

The axially directed joining ends 17 are provided as contact points for the connection to the associated phase connections 4 and are molded integrally, that is to say in one piece or monolithically, onto the busbars 16. The axially directed contact lugs 13 as contact points for contacting or electrically conductively connecting the associated coil end 10 are also integral constituents of the busbars 16. The contact lugs 13 are embodied in particular as welding lugs for a welded connection, preferably for a laser welded connection, to the coil ends 10, which in particular are stripped. The busbars 16 with their joining ends 17 and contact lugs 13 are embodied here for example as stamped and bent parts made of a copper material.

The phase contacts 4 are embodied in this embodiment as approximately rectangular contact lugs in the form of a stamped and bent part. The long sides of the particular phase connection 4 are oriented here in the axial direction A, wherein the narrow sides are oriented for example radially. The particular phase connection 4 protrudes axially upward at the stator end face supporting the interconnection housing 11. For support and stabilization, the phase contact 4 sits in the assembled or joined state of the electric motor 1 in a holding receptacle of the interconnection housing 11 of the contact apparatus referred hereinafter as a support portion 18. The phase connections 4 are provided as insulation displacement contacts or connection and for this purpose are provided on the free end side with a receiving slot 19 for a blade contact of the motor electronics unit 6.

As can be seen relatively clearly from FIGS. 3 and 4 , each phase connection 4 has an axially extending contact portion 4 a and a connection portion 4 b running orthogonally thereto, in which there is formed a preferably rectangular recess, not described in greater detail. The joining end 17 of the busbar 16 to be connected to a particular phase connection 4 reaches through the corresponding recess of the connection portion 4 b of the phase connection 4. The joining end 17 of the corresponding busbar 16 to be connected to a particular phase connection 4 is embodied as a cross-sectional reduction or tapering 20 of the busbar 16 at the bar end or connection end of the busbar facing the particular phase connection 4. The joining end 17 is preferably approximately L-shaped, wherein the vertical limb of the L forms the tapering 20. The cross-sectional area of the tapering 20 is smaller here than that of the adjoining portion of the joining end 17. The joining end 17 in the region of the tapering 20 is smaller in cross section than the cross section of the recess in the boom-like connection portion 4 b of the phase connection 4.

In the shown joined stated, a form-locking and integrally bonded connection 23, in particular a welded connection, is produced between the joining end 17 of the busbar 16 and the connection portion 4 b of the phase connection 4, expediently by means of laser welding. This is carried out when the joint is produced and the components (busbars 16 and/or phase connections 4) of the contact apparatus 5 are overmolded, that is to say the interconnection housing 11 is completed. This housing then has a preferably planar, annular base portion 21. In this state, the joining end 17 protrudes through an opening 22 in the interconnection housing 11 to the upper side of the latter formed by the base portion 21. The joining end 17 or tapering 20 thereof of the busbar 16 is deformed in the connection produced by means of laser welding (form-locking and integrally bonded joint) to the phase connection 4. These connections are accessible following the overmolding of the corresponding portions of the busbars 16.

The connection portions 4 b of the phase connections 4 run in the circumferential direction or tangentially based on the annular base portion 21 of the connection housing 11, whereas the joining ends 17 of the busbars 16 to be connected to the phase connections 4 are oriented axially. In this way, the joining ends 17 of the busbars reach through the recesses 20 in the phase connections. The contact lugs 13 of the busbars 16 are positioned in a radially inner region of the interconnection housing 11, opposite the connection portions 4 b of the phase connections 4 and their connection or contact points to the busbars 16.

FIG. 4 shows the contact apparatus 5 (without interconnection housing 11) according to FIG. 3 in a plan view with the busbars and phase connections of the two three-phase sub-systems as well as their interconnection to the coils. Here, for reasons of clarity and distinguishability of the three phases (U, V, W) of each of the two sub-systems, in FIG. 4 the busbars corresponding to FIG. 3 provided for connection to the two coils of each phase (U, V, W) are shown only for the sub-system shown on the left, whereas the busbars provided for connection of the two coils of each phase (U, V, W) are shown by dashed lines in the sub-system shown on the right.

Hereinafter, the phase connections, the coils and coil ends thereof as well as the busbars are provided with indexed letters instead of the numbers (4, 7, 10, 16) used in FIGS. 1 to 3 . Here, the designation P_(n) (with n = 1, 2, ..., 6) is used for the phase connections, and the designation SP_(n) (with n = 1, 2, ..., 12) is used for coils, and the designation SP_(nm) (with n = 1, 2, ..., 6 and m = 1, 2, ..., 6) is used for the coil ends of the first sub-system (in FIG. 4 the left half of the figure and FIG. 5 a ), and the designation S_(n) (with n = 1, 2, ..., 14) is used for the busbars.

FIGS. 5 a and 5 b show schematically the two three-phase sub-systems with the associated coils, busbars and phase connections. In the sub-system shown on the right in FIG. 4 and schematically in FIG. 5 b , the coil ends are not designated in greater detail, for reasons of clarity.

In the left half of FIG. 4 , three busbars S_(n) approximately U-shaped in cross section can be seen, which each connect two coil ends SP_(nm). Here, the coil ends SP_(nm) are those of the coils SP_(n) that are connected to one another within one of the phases U, V, W. The busbars S_(n) used in the first sub-system provided here in a three-phase embodiment are identical in respect of their dimensions, i.e. their length and cross section as well as their shape or geometry. The same is true for the busbars S_(n), shown merely as dashed lines, of the other, second sub-system shown on the right in FIG. 4 .

Specifically, in the case of the sub-system shown on the left in FIG. 4 in conjunction with FIG. 5 a , a first coil SP₁ and second coil SP₂ are connected via a first busbar S₁ within the same phase — here for example the phase U — via one of the coil ends SP₁₂ and SP₂₂ of each of said coils. The other coil end SP₁₁ of the first coil SP₁ is connected via a second busbar S₂ to a coil end SP₄₁ of a fourth coil SP₄ of a second phase — here for example the phase V — and to a coil end SP₅₁ of a fifth coil SP₅ of the third phase — here for example the phase W. For this purpose, the second busbar S₂, which forms the star point B, has connection contacts, not designated in greater detail, and therebetween two busbar portions S₂₁ and S₂₂ of different portion length. The other coil end SP₂₁ of the second coil SP₂ is connected to a third busbar S₃, which is in turn connected to the connection portion 4 b of the phase connection 4, designated here by P₁, of the phase U in the described form-locking and integrally bonded joint.

The fourth coil SP₄ associated with the second phase V is connected with its other coil end SP₄₂ to a fourth busbar S₄, which is connected to a coil end SP₃₂ of a third coil SP₃, which with the fourth coil SP₄ forms the phase V. The other coil end SP₃₁ of the third coil SP₃ is connected to a fifth busbar S₅, which is in turn connected to the connection portion 4 b of the phase connection 4, designated here by P₂, of the phase V in the described form-locking and integrally bonded joint.

The fifth coil SP₅ associated with the third phase W is connected by its other coil end SP₅₂ to a sixth busbar S₆. which is connected to a coil end SP₆₂ of a sixth coil SP₆, which with the fifth coil SP₅ forms the phase W. The other coil end SP₆₁ of the sixth coil SP₆ is connected to a seventh busbar S₇, which is in turn connected to the connection portion 4 b of the phase connection 4, designated here by P₃, of the phase W in the described form-locking and integrally bonded joint.

The dimensions of the busbars S₁, S₄ and S₆, which connect the coil pairs SP₁₂, SP₃₄ and SP₅₆ of the phases U, V and W respectively, are the same in respect of their dimensions and can thus be provided advantageously as identical parts. The dimensions of the busbars S₂, S₃, S₅ and S₇ are different, wherein their bar length and/or bar cross section is set in such a way that the electrical resistances R of all three phases U, V, W are the same and thus the electrical resistance of the first sub-system of the stator winding 3, said sub-system being embodied in a star circuit by means of the contact apparatus 5, is symmetrical.

The symmetry (resistance symmetry) can be specified advantageously as a quotient of the difference of the maximum and minimum resistance between two phases and the mean resistance between the phases (symmetry = (maximum resistance between two phases — minimum resistance between two phases)/mean resistance between the phases). The value of the symmetry is advantageously <1 %.

This resistance symmetry is also set in the sub-system shown on the right in FIG. 4 by means of the busbars used there. For simplification, the coil ends of the further six coils S₇ to S₁₂ of this (second) sub-system with the phase connections P₄, P₅ and P₆ are not designated in greater detail.

Specifically, in the sub-system shown in the right in FIG. 4 in conjunction with FIG. 5 b , a seventh coil SP₇ and an eighth coil SP₈ are connected via an eighth busbar S₈ within the same phase — here for example the phase U — via one of the coil ends of each of said coils. The other coil end of the seventh coil SP₇ is connected via a ninth busbar S₉, which in turn forms the star point B of the star circuit, to a coil end of a tenth coil SP₁₀ of a second phase — here for example the phase V — and to a coil end of an eleventh coil SP₁₁ of the third phase — here for example the phase W. For this purpose, the busbar S₉ has three connection contacts, not designated in further detail, and therebetween two busbar portions S₉₁ and S₉₂ of different portion length. The other coil end of the eighth coil SP₈ is connected to a tenth busbar S₁₀, which is in turn connected to the connection portion 4 b of the phase connection 4, designated here by P₄, of the phase U in the described form-locking and integrally bonded joint.

The coil SP₁₀ associated with the second phase V is connected by its other coil end to an eleventh busbar S₁₁, which is connected to a coil end of a ninth coil SP₉, which with the coil SP₁₀ forms the phase V. The other coil end of the coil SP₉ is connected to a twelfth busbar S₁₂, which is in turn connection to the connection portion 4 b of the phase connection 4, designated here by P₅, of the phase V in the described form-locking and integrally bonded joint.

The coil SP₁₁ associated with the third phase W is connected by its other coil end to a thirteenth busbar S₁₃, which is connected to a coil end of a twelfth coil SP₁₂, which with the coil SP₁₁ forms the phase W. The other coil end of the coil SP₁₂ is connected to a fourteenth busbar S₁₄, which is in turn connected to the connection portion 4 b of the phase connection 4, designated here by P₆, of the phase W in the described form-locking and integrally bonded joint.

The dimensions of the busbars S₈, S₁₁ and S₁₃ are again the same in respect of their dimensions and those of the busbars S₁, S₄ and S₆. The dimensions of the busbars S₉, S₁₀, S₁₂ and S₁₄ are different, wherein their bar length and/or bar cross section is again set in such a way that the electrical resistances R of all three phases U, V, W are the same and thus the electrical resistance of the second sub-system of the stator winding, said sub-system being embodied in a star circuit by means of the contact apparatus 5, is symmetrical. The dimensions of the busbars S₂ and S₉ are the same in the exemplary embodiment, whereas the dimensions of the busbars S₁₀, S₁₂ and S₁₄ are different from one another and also in relation to the busbars S₃, S₅ and S₇.

As can be seen for example with reference to the busbars S₇ and S₁₂, their busbar length is only small in comparison to the distance between the coil end SP₆₁ and the phase connection P₃ or between the corresponding coil end of the coil SP₁₀ and the phase connection P₅, and therefore a suitable shape (geometry) of the busbars S₇ and S₁₂ is selected by shaping the corresponding busbars S₇ and S₁₂ in a loop-like or undulating or meandering manner in order to provide the necessary electrical resistance.

The invention is not limited to the above-described exemplary embodiment. Rather, other variants of the invention can be derived herefrom by a person skilled in the art, without departing from the subject matter of the invention. In particular, all individual features described in conjunction with the exemplary embodiments can also be combined with one another in other ways without departing from the subject matter of the invention.

In addition, the invention can be used not only in the application specifically presented, but also in a similar embodiments in other motor vehicle applications, for example in door and tailgate systems, in window lifters, in vehicle locks, in adjustable seat and systems and interior systems, as well as in electric drives, control systems, sensors and their arrangement in the vehicle.

LIST OF REFERENCE SIGNS

-   1 electric motor -   2 stator -   3 stator winding -   4 phase connection/contact -   4 a contact portion -   4 b connection portion -   5 contact apparatus -   6 motor electronics unit -   7 coil -   8 stator main body/assembly -   9 coil/winding support -   10 coil end -   11 interconnection housing -   12 through-opening -   12 a opening -   12 b guide slot -   13 contact lug -   14 detent tongue -   15 groove -   16 busbar -   17 joining end -   18 support portion/holding receptacle -   19 receiving slot -   20 tapering -   21 base portion -   A stator axis/axial direction -   B star point -   P_(n) phase connection -   S_(n) busbar -   S_(nm) busbar portion -   SP_(n) coil -   SP_(nm) coil end -   U, V, W phase 

1-10. (canceled)
 11. A stator of an electric motor, the stator comprising: a stator main body having an end face; a multi-phase stator winding including a plurality of coils supported by said stator main body, each of said coils having two coil ends; a contact apparatus disposed on said end face of said stator main body; an interconnection housing; a plurality of busbars received by said interconnection housing for interconnecting said coils; a plurality of phase connections each connected to a respective one of said busbars; said stator winding having phases each formed by at least one of said coils and at least one of said busbars as well as one of said phase connections; and said busbars having dimensions set to provide the same electrical resistance of all of said phases of said stator winding.
 12. The stator according to claim 11, wherein said dimensions of said busbars are set to provide the same electrical resistance of said busbars.
 13. The stator according to claim 11, wherein said busbars have at least one of a bar length or a bar cross section set to provide the same electrical resistance of said phases of said stator winding.
 14. The stator according to claim 11, wherein said busbars used for connection of said coils in a particular phase is the same for each of said phases.
 15. The stator according to claim 11, wherein each of said busbars has at least one connection contact for contacting a respective one of said coil ends.
 16. The stator according to claim 11, wherein: said coils are interconnected in a star circuit having a star point; and an individual busbar has three connection contacts as well as a first and a second busbar rail portion producing said star point of said star circuit.
 17. The stator according to claim 16, wherein said busbar rail portions have different portion lengths.
 18. The stator according to claim 11, wherein said stator winding is formed redundantly with two sets of three phases.
 19. The stator according to claim 11, wherein each of said phase connections at least one of: have a connection portion with a recess, and said busbars to be connected to said phase connections each have a joining end reaching through said recess of said connection portion of a respective said phase connections, or have a configuration as a clamp contact or an insulation displacement contact.
 20. An electric motor, comprising a stator according to claim
 11. 